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Old 10-28-2015, 12:45 AM   #1
NemesisX's Avatar
Join Date: Mar 2012
Feedback Rating: (0)
Posts: 7

Experience: 2 years

2009 GS500F

shimming valves in GS500

I am doing the shim to cam clearances on my bike. Currently they are:

Left Exhaust .06/275 Right Exhaust .04/275
Left Intake .04/272 Right Intake .04/278

Specs are .03-.08, so they're all in spec. I'm trying to move them to the looser side of things.

Based on the shims available to me I can go either:

Choice 1:
Left Exhaust .06/275 Right Exhaust .07/272
Left Intake .06/270 Right Intake .07/275

Choice 2:
Left Exhaust .09/272 Right Exhaust .09/270
Left Intake .06/270 Right Intake .07/275

From what I've learned, it's best to have the L/R exhaust valves and L/R intake valves matching (if possible), and better to have the exhaust valves (and valves in general) looser than tighter. If that's correct, it looks like choice #2 is best.

I just wanted to confirm with those experienced. This is only the second time I've done valves and the first time on a motorcycle or a shim over bucket valve train. GStwins suggested that choice 2 is the better one, but noted that my current clearances are good because 3 of the 4 match. I was under the impression that it doesn't matter if the intake valve clearance is matched with the exhaust clearance (only that L exhaust = R exhaust and L intake = R intake).

And I can't leave .04 on both intakes because then I would have to leave the 272 in the left intake and couldn't use it for the left exhaust. I can't source any half size shims on short notice, and I'm unwilling to sand/grind.

Opinions? Thanks!
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